I tried to download my Facebook data once and found that it had all my ancient and deleted posts, ancient relationship status, ancient cities of dwelling, etc.
Anyway how would filling in garbage help in deleting Facebook account?
I think the idea is to seed mistrust in the data because there is no way to distinguish between the genuine and the fake data you put on your account. So the fake data makes the genuine practically useless.
Exactly. Taking it to the next level, leave your own tracking info in the fakery, e.g. "favorite vacation: France". Then if someone cold-spams you with tickets to Paris, you'll know why.
Anyway how would filling in garbage help in deleting Facebook account?